As the human population grows, cities get larger and industry expands. These changes mean that the area available for natural environments is reduced. Many species have been badly affected. However, many industries are now trying to make their operations more sustainable.
Loss of species diversity
Human actions have caused many native species to become extinct. A species is said to be extinct when nobody has seen it in the wild for over 50 years and the last known individual has died. In the past 200 years more than 125 species of Australian native plants and animals have become extinct.
Hunting, changes to the environment, and habitat loss have caused many more species to become threatened.
Threatened organisms can be classified into one three groups, depending on how great the threat to their survival appears to be.
- Endangered species are close to extinction and very small numbers remain. Examples are the helmeted honeyeater, the blue whale, the beaked gecko and the Leadbeater’s possum
- Vulnerable species are experiencing a rapid population decline and are in danger of becoming extinct if the drop in numbers continues. Examples of vulnerable animals are the mountain pygmy-possum, the giant Gippsland earthworm, the Mallee fowl, the bilby and the diamond python.
- Rare species have low numbers and are often spread out over a large area. Although the populations may be small, they are not decreasing. Rare organisms include the eastern wallaroos, the leafy sea dragon, the powerful owl and the alpine tree.
Effect of an industry
Sumatra is one of the islands of Indonesia. It has a huge range of plant and animals species, some of which are found only on this island.
The The Sumatran elephant, Sumatran tiger (Figure 5.4.3), Sumatran rhino and Sumatran orang-utan are four species that are critically endangered because their habitat is disappearing. These species live in the rainforests of Sumatra. However, Sumatra has lost almost 50% of its tropical rainforests in the past 35 years.
The rainforests of Sumatra are logged and burned, and then oil palm plantations are established. Indonesia is the world’s largest producer of palm oil and the industry brings money into the country and provides employment for many people.
Logging
Trees growing in Australia’s forests are a valuable source of timber. Timber is used in construction, furniture making and as wood pulp for the production of paper. Figure 5.4.5 shows how the forests, and the habitats the forests contained, are destroyed when the trees are removed.
Animals’ homes and food sources are Lost. More light is able to reach the ground and the types of plants able to grow there change.
In New South Wales the aim is to manage the forests in a sustainable way. Sustainably managed forests should:
- Provide timer both now and into the future
- protect forest environments to maintain biodiversity
- provide community amenities
Mining
Mining is an important industry in NSW.
Gold, copper, lead, silver and zinc are some of the metals mined. However, coal mining is the most important mining industry in the state.
Locally mined coal produces 89 percent of the total electricity needs in NSW. Mining has the potential to cause major damage to environments.
In open-cut mining the surface soil and rock is scraped away to access the resource underneath. All the habitats that were there are destroyed. There have also been situations where poisonous chemicals from the mines pollute waterways, causing damage to these habitats and the organisms that Jive in them. Loose soil also washes into rivers and creeks and destroys the habitat of water plants, which cannot grow in muddy water.
Agriculture
A large proportion of the total land area has been cleared of native vegetation. These agricultural areas provide very different habitats from the native vegetation.
Fertilisers and pesticides used on the crops may wash into rivers from the farmland, causing changes in river and wetland ecosystems.
Scientists have developed new varieties of crops and breeds of animals better able to cope with Australian conditions. Scientists have also developed ways of growing consistently good quality fruit and vegetables that can be produced as cheaply and quickly as possible.
Salt-tolerant wheat
Some parts of Australia’s soils have a high salt content. Not all plants can grow in salty soils and as the area of salty land increases the amount of food produced decreases. If salt reaches the leaves of wheat, the plant cannot carry out photosynthesis.
In 2012, Australian scientists from the University of Adelaide produced a variety of durum wheat that is able to grow in soil with high levels of salt. The scientists created the new variety by using two varieties of wheat as the parent plants and growing plants that have characteristics of both parents. The parent plants used were:
- a modern variety of durum wheat that produces a large amount of grain- it has a high yield
- An ancient wheat variety that has the ability to remove the salt from the water as the water moves from the roots of the leaves. The old variety has a low yield.
The new variety of wheat scientists have created has characteristics of both parents plants- the high-yield characteristic of modern wheat, and an ability to tolerate salt. It has taken about 15 years of research to create this new variety. Now that scientists have been successful in making salt- tolerant durum wheat, they hope to use this knowledge to create a variety of bread wheat that is able to grow in salty soils.
Droughtmaster cattle
Cattle are not native to Australia, most were imported from Europe. The conditions in Australia are very different from Europe and farmers often struggled to keep their cattle in good condition for the beef market. In the early 1900s, pioneer cattle breeders in North Queensland saw a need for cattle that:
- Could tolerate hot weather
- Could make best use of the limited nutrition provided by the native pasture grasses
- could walk long distances to access water and feed
- were resistant to tricks
- produced good quality meat
- give birth to their salves easily
Brahman cattle, originally came from India. They have more sweat glands than European cattle, which makes them better able to tolerate hot weather. Their oily skin helps repel insect pests and they are more resistant to parasite and disease.
Shorthorn cattle are a breed from the United Kingdom that produce good meat. Some of the original Australian Shorthorns came from England with the First Fleet.
Cattle breeders mated Brahman cattle with beef Shorthorn. This process of mating one breed of cattle with another is known as cross breeding. at each generation the offspring that showed the best characteristics were selected and then mated. After many years of cross breeding, animals with all the desired characteristic were produced.
This new breed was called Drought-master. It is found in all Australian mainland states, with the largest numbers north of the New South Wales border. It is able to cope with harsh conditions and is now the second-most common breed in Australia.
Cloning plants
Plants also reproduce using a male and a female, but some plants can also reproduce using parts of only one parent plant. When they reproduce in this way the offspring (babies) are exactly the same as the parent. The offspring are clones of each other.
Cloning of plants has been used by farmers and gardeners for centuries.
The advantage of cloning include:
- Thousands of plants can be produced from one parent plant.
- The best plants can be selected for cloning- plants that are resistant to disease or produce larger, sweeter or more colorful fruit.
- The quality of the plant or the fruit is known from the beginning
- Cloned plants all grow at the same rate and therefore all fruit is ready for harvest at the same time.
The disadvantages of cloning are:
- All plants are identical and all will be easily attacked by the same pests and affected and may die from the same diseases
- Cloned plants are often sterile. This means that they do not produce seeds from which new plants can be grown. If the plant population was wiped out there would be no way of growing plants to replace them.
Banana suckers
All the bananas you buy in the shops have all been grown by suckers and are all exactly the same. A big risk of them being all the same is that they will be affected in the same way by a disease.
A disadvantage of this is that there are diseases of banana trees that could destroy the whole banana crop in Australia. This is why bringing Banana trees from overseas is illegal and imports are strictly controlled. An advantage of the trees being the same is that the fruit they produce is also the same and bananas in the shops are all of the same quality.
<aside> 💡 Exam Technique. Discuss: means to give disadvantages and advantages.
Q: Discuss the use of cloning in bananas. (2 marks) A: An advantage of having cloning in bananas is that the fruit produced will all be the same quality. However a disadvantage is that a disease that affects of the cloned banana plants can affect all of the banana plants.
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Grafting fruit trees
Horticulturalists grow fruit trees from seeds.
- Every seed is unique
- Cuttings are a art of the stem, leaf or root that is able to grow into a new plant.
- Cuttings are used when horticulturalists find a tree that produces very good quality fruit they will take cuttings from that tree.
Urbanization
Towns and cities are built on land that was once a natural ecosystem. Native vegetation and the animals that have once lived there no longer have their habitat. Some animals that live in urban areas thrive there, like pigeons
